DE 10 2008 033 044 B3 discloses an annular filter element for a filter device, wherein the fluid to be purified can flow through the filter element radially from the outside to the inside, so that the enclosed inner flow chamber forms the clean side. A radially extending flow channel, by way of which the purified fluid is discharged from the enclosed flow chamber to the outside, is introduced into the wall of the filter medium body of the filter element which is designed as a pleated filter.
Reference is also made to DE 10 2010 041 657 A1 and EP 2 152 385 B1 with regard to the additional prior art.